Hi;

My suggestion originally was to apply the varnish to the kayak strictly with a lint-free rag, as woodworkers have done for years. In other words, skip the brush, roller, or whatever. I have used linseed oil on a rag to repair scratches on varnished wooden furniture, but never varnish. Kent has now found out that varnish works well also! If it works as well as the linseed oil, the scratches virtually disappear - Although as Dean says, you will probably still be able to feel deeper scratches. Kent, you might comment on just how well they filled for you.

Best of Luck, Spidey